1. Field of the Invention
This invention relates to energy transfer and conversion devices, such as pumps, engines and fluid proportioning apparatus, and more particularly, to a positive displacement swept volume rotary apparatus in which rotary motion is directly developed without the occurrence of low speed slippage.
2. Brief Description of the Prior Art
Various attempts have been previously made to concurrently achieve in a single machine, the advantages which characterize a positive displacement reciprocating engine or pump, and those which characterize fluid driven rotary turbines delivering rotary motion as a direct result of the transfer of energy from a power fluid to the turbine. In the case of positive displacement, reciprocating pumps and engines, the energy transfer from the power fluid to a piston is accomplished efficiently, but the net output of useful work is reduced significantly because of energy dissipation involved in the reversal of piston motion, throwing of valves, operation of associated gear trains, etc. In turbines, the uni-directional continuous operation of the rotor eliminates the energy wastage inherent in the necessity for piston reversal, operation of valving and the like, but generally entails some "slippage" in the sense of by-passing of some of the power fluid by the turbine blades with the result of reduction in the efficiency of energy transfer directly from the fluid to the turbine blades, particularly at start-up and low speeds.
Among recent devices proposed for combining the rotary motion advantages of the turbine with the principles of positive displacement energy transfer, several are described in U.S. Pat. Nos. 3,136,262; 3,166,019; and Re. 25,818, all issued to Krawacki. The Krawacki rotary motion apparatus is characterized by a rotor disposed within a ported stationary housing, and defining within the housing, a working fluid accommodation space between the rotor and housing in communication with the housing ports. A plurality of elongated sliding vanes are slidably mounted in spaced slots extending axially along the rotor, and partition the working fluid accommodation space into chambers. The sliding vanes are cammed in a reciprocating motion by stationary cam surfaces carried on the housing adjacent opposite ends of the rotor, and by virtue of the provision of selectively located slots in the vanes, the vanes alternately open close the chambers to the housing ports as the vanes are reciprocated. The Krawacki rotary motion apparatus is complex, requires careful and accurate machining of parts and entails significant energy losses in the frictional sliding of the vanes in slots extending over a major portion of the entire length of the rotor.